Database
BASIC REAL AND COMPLEX FUNCTIONS
Basic trigonometry
The natural logarithm on complex numbers
logimcld
Metamath Proof Explorer
Description: The imaginary part of the logarithm is in ( -upi (,] pi ) .
Deduction form of logimcl . Compare logimclad . (Contributed by David Moews , 28-Feb-2017)
Ref
Expression
Hypotheses
logimcld.1
⊢ ( 𝜑 → 𝑋 ∈ ℂ )
logimcld.2
⊢ ( 𝜑 → 𝑋 ≠ 0 )
Assertion
logimcld
⊢ ( 𝜑 → ( - π < ( ℑ ‘ ( log ‘ 𝑋 ) ) ∧ ( ℑ ‘ ( log ‘ 𝑋 ) ) ≤ π ) )
Proof
Step
Hyp
Ref
Expression
1
logimcld.1
⊢ ( 𝜑 → 𝑋 ∈ ℂ )
2
logimcld.2
⊢ ( 𝜑 → 𝑋 ≠ 0 )
3
logimcl
⊢ ( ( 𝑋 ∈ ℂ ∧ 𝑋 ≠ 0 ) → ( - π < ( ℑ ‘ ( log ‘ 𝑋 ) ) ∧ ( ℑ ‘ ( log ‘ 𝑋 ) ) ≤ π ) )
4
1 2 3
syl2anc
⊢ ( 𝜑 → ( - π < ( ℑ ‘ ( log ‘ 𝑋 ) ) ∧ ( ℑ ‘ ( log ‘ 𝑋 ) ) ≤ π ) )